1 /* sem_post -- post to a POSIX semaphore. Generic futex-using version.
2 Copyright (C) 2003, 2004, 2007, 2008 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Jakub Jelinek <jakub@redhat.com>, 2003.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
22 #include <lowlevellock.h>
23 #include <internaltypes.h>
24 #include <semaphore.h>
30 struct new_sem *isem = (struct new_sem *) sem;
32 __typeof (isem->value) cur;
36 if (isem->value == SEM_VALUE_MAX)
38 __set_errno (EOVERFLOW);
42 while (atomic_compare_and_exchange_bool_acq (&isem->value, cur + 1, cur));
44 atomic_full_barrier ();
45 if (isem->nwaiters > 0)
47 int err = lll_futex_wake (&isem->value, 1,
48 isem->private ^ FUTEX_PRIVATE_FLAG);
49 if (__builtin_expect (err, 0) < 0)